Differential signal transmission cable property evaluating mechanism and evaluating method therefor

Abstract

A differential signal transmission cable property evaluating mechanism includes a substrate having a signal line pad to be connected with a signal line conductor of a differential signal transmission cable and a ground pad to be connected with a shield conductor of the differential signal transmission cable, a pressing member for pressing the signal line conductor to the signal line pad, a shield conductor holding sheet including an elastic insulating sheet and a metal foil provided over one side of the elastic insulating sheet, the shield conductor holding sheet provided for indirectly connecting the shield conductor and the ground pad to each other by contacting the metal foil with the shield conductor and the ground pad, and a clip for fixing the shield conductor holding sheet.

What is claimed is: 
     
       1. A differential signal transmission cable property evaluating mechanism, comprising:
 a substrate comprising:
 a signal line pad to be connected with a signal line conductor of a differential signal transmission cable; and 
 a ground pad to be connected with a shield conductor of the differential signal transmission cable; 
 
 a pressing member for pressing the signal line conductor into a direct contact with the signal line pad; 
 a pair of shield conductor holding sheets, each comprising an elastic insulating sheet and a metal foil provided over one side of the elastic insulating sheet, the each shield conductor holding sheet provided for indirectly electrically connecting the shield conductor and the ground pad to each other by contacting the metal foil with the shield conductor and the ground pad; 
 a clip for fixing the shield conductor holding sheet onto the substrate; and 
 a notch provided at an edge of the substrate for accommodating a terminal of the differential signal transmission cable, 
 wherein the ground pad comprises plural pads provided on both sides of the notch respectively on both surfaces of the substrate, and 
 wherein the shield conductor is connected to each of the plural pads provided on the both surfaces of the substrate by one pair of the shield conductor holding sheets sandwiching the shield conductor therebetween on the both surfaces of the substrate. 
 
     
     
       2. The differential signal transmission cable property evaluating mechanism according to  claim 1 ,
 wherein the signal line pad is provided at a position collinear with the signal line conductor when the terminal of the differential signal transmission cable is accommodated in the notch. 
 
     
     
       3. The differential signal transmission cable property evaluating mechanism according to  claim 1 , wherein the substrate comprises a material having a relative permittivity of 3.8 or less at a frequency of 1 MHz. 
     
     
       4. The differential signal transmission cable property evaluating mechanism according to  claim 1 , further comprising:
 a connection mechanism to connect the substrate to a measuring instrument. 
 
     
     
       5. The differential signal transmission cable property evaluating mechanism according to  claim 1 , further comprising:
 an electrically conductive paste provided on a surface of the ground pad. 
 
     
     
       6. The differential signal transmission cable property evaluating mechanism according to  claim 1 , wherein the pressing member comprises a transparent material having a relative permittivity not more than 3.2 at a frequency of 1 MHz. 
     
     
       7. The differential signal transmission cable property evaluating mechanism according to  claim 1 , wherein the pressing member comprises a material having a dielectric loss tangent not more than 0.01 at a frequency of 1 MHz. 
     
     
       8. The differential signal transmission cable property evaluating mechanism according to  claim 1 , wherein the elastic insulating sheet comprises a silicon sheet and the elastic insulating sheet and the metal foil are bonded together by a silicon based adhesive. 
     
     
       9. The differential signal transmission cable property evaluating mechanism according to  claim 1 , wherein the plural pads of the ground pad of the substrate surround a ground of a differential signal transmission cable. 
     
     
       10. The differential signal transmission cable property evaluating mechanism according to  claim 1 , wherein the signal line pad is provided at a position collinear with the signal line conductor, and
 wherein the elastic insulating sheet comprises a silicon sheet. 
 
     
     
       11. The differential signal transmission cable property evaluating mechanism according to  claim 1 , wherein the elastic insulating sheet and the metal foil are bonded together by a silicon based adhesive. 
     
     
       12. A differential signal transmission cable property evaluating method, comprising:
 evaluating a property of a differential signal transmission cable including preparing of the differential signal transmission cable for using the differential signal transmission cable property evaluating mechanism according to  claim 1 . 
 
     
     
       13. The differential signal transmission cable property evaluating method according to  claim 12 , comprising:
 evaluating the property of the differential signal transmission cable having a common mode time domain reflectometry impedance of 40Ω to 50Ω. 
 
     
     
       14. A differential signal transmission cable property evaluating method, comprising:
 evaluating a property of a differential signal transmission cable including preparing of the differential signal transmission cable for using the differential signal transmission cable property evaluating mechanism according to  claim 2 . 
 
     
     
       15. A differential signal transmission cable property evaluating method, comprising:
 evaluating a property of a differential signal transmission cable including preparing of the differential signal transmission cable for using the differential signal transmission cable property evaluating mechanism according to  claim 3 . 
 
     
     
       16. A differential signal transmission cable property evaluating method, comprising:
 evaluating a property of a differential signal transmission cable including preparing of the differential signal transmission cable for using the differential signal transmission cable property evaluating mechanism according to  claim 4 . 
 
     
     
       17. A differential signal transmission cable property evaluating method, comprising:
 evaluating a property of a differential signal transmission cable including preparing of the differential signal transmission cable for using the differential signal transmission cable property evaluating mechanism according to  claim 5 . 
 
     
     
       18. A differential signal transmission cable property evaluating method, comprising:
 evaluating a property of a differential signal transmission cable including preparing of the differential signal transmission cable for using the differential signal transmission cable property evaluating mechanism according to  claim 6 . 
 
     
     
       19. A differential signal transmission cable property evaluating method, comprising:
 evaluating a property of a differential signal transmission cable including preparing of the differential signal transmission cable for using the differential signal transmission cable property evaluating mechanism according to  claim 7 . 
 
     
     
       20. A differential signal transmission cable property evaluating method, comprising:
 evaluating a property of a differential signal transmission cable including preparing of the differential signal transmission cable for using the differential signal transmission cable property evaluating mechanism according to  claim 8 .